Telephone-exchange system.



F. A. STEARN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED 0032s. 1916.

1,258,374. Patented Mar. 5, 1918.

10 am. 5H.

A I l /H van for: Frank/in A. .Sfearn.

by A/fyL UNITED STATES PATENT onnroa FRANKLIN A. s'rnann, or ra'rnnson, new annsnr, Assrenon tro wnsrnnn nnnornro COMPANY, rnoonrona'rnn, or new YonK, n. Y., A oonronn'rron or new "roan.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Mar. 5, 1918.

Application filed October 28, 1916. Serial No. 128,307.

To all whom it may concern: f

Be it known that I, FRANKLIN A. Srnaun, a citizen of the United States, residing at Paterson, in the county of Passaic and State of New Jersey, have invented certain new and useful Improvements in TelephoneExchange Systems, of which the following is a lull, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to improvements in operators listening key circuits.

It is the object of this invention to provide means whereby an operator may listen from one cord to another at a high rate of speed.

A feature of the invention is the use of a pair of relays common to all the cords of a position whose interaction controls the disconnection of an operators head set from a cord circuit and its connection to a second cord.

It is thought that the invention will best be understood from the following dctailed description, reference being had to the acco1n panying drawing. In the drawing the, an-

swering end of the connecting operatofis.

cord circuit is diagrammatically shown at the left, while at the right is shown a portion of the listening circuits of a second cord at the same operators position. y

The operation of the system has been described in connection with a sequence switch which controls a district selector, the system in which this sequence switch used being preferably of the type disclosed inPatent No. 1,168,319. The invention is not restricted to use with such a system, however, since by making changes obvious to one skilled in the art, it may readily be adapted for use with any operators connecting link circuit.

Assuming that the position is idle an a call comes in over the line terminating in jack 1, the operator will be informed in the well-known manner by the lighting of the usual line lamp (not shown). She then inserts a plug 2 into jack 1, whereupon a circuit will be completed for relay 3 from ground, winding of relay 3, sleeve contacts of plug 2 and jack 1, to grounded battery, through the winding of the well-known cutoli relay (not shown). At its inner armature relay 3 completes a circuit from grounded battery, armature andbackcontact of relay 4:, conductor 5, inner armature and that j front contact of relay 3, contact 102 righthand armature and back contact of relay 6, right-hand winding of relay 7, to ground. Belay 71s energized and locks itself to conductor 5 at its inner right-hand armature and front contact. At its outer right-hand armature and front contact parallel circuits are completed for relays 6 and 9. Relay 9 upon energization, connects the calling line to theoperators telephone apparatus. Relay 6 upon energization, locks itself to grounded battery at the outer armature and front contact of relay 3. left-hand armature completes a locking circuit for itself from grounded battery, ar-.

.mature and back contact of relay 10, winding of relay 4L, inner left-hand armature and front contact of relay 7 and left-hand winding of relay 7, to ground. Relay ll is energized in this circuit and opens the locking circuit through the right-hand winding of relay 7. At its middle left-hand armature, relay? completes a circuit from grounded battery power magnet of sequence switch 100, middle left-hand armature and front contact of relay 7, contact 103 to ground, which moves this sequence switch out of position 1 and into position 2. Further progress olthis sequence switch will take place in the well-known manner.

It the operator desires to listen out after learning the number or the wanted line, she depresses listening-out key 16, completing a circuit from grounded battery, contacts of key 16 and winding of relay 10, to ground. 1lelay 1O attracts its armature and opens the circuit of relay hand the locking circuit through the left-hand winding of relay 7. Since the locking circuit through the righthand winding of relay 7 had been broken at the contacts of relay .1: upon its energize. tion, relay? deenergizes and in doing so, opens the circuit of relay 9, thereby disconnecting the operators telephone set from the talking strands of the cord circuit. The release of the listening-out key 16 cleenergizes relay 10. i

It now we assume that a call comes in which the operator answers with the cord whose listenlng circuits are shown at the right of the dotted line, the energization .mature and back contact of relay l, con

Relay 7 at its inner ductors 5, l7, inner armature and front contact of relay 3, right-hand armatureand back contactof relay 6, right-hand'winding of relay 7 to ground. Relay 7 at its outer right-hand armature, energizes relay 6and a relay (not shown) corresponding to relay 9 of the first cord, in the manner previously described for relays 6 and 9, an relay 7 at its inner left-hand armature and front contact locks itself to grounded battery over conductor 18, throughthe winding of relay 4 and the armature and backcontact of relay 10. From this pointthe operation of the circuits is similar to thatpreviously described for the cord shown at the left of the dotted line.

If the operator should plug in on a sec- 011d cord, such as that shown at the right of the drawing, before depressing listening- "out key 16, the operation of relay 3 will complete a circuit from grounded battery,

outer armature and front contact of relay 3,

' again on the cord at theleft, she will depress listening key 20 of such cord. A circuit will thereupon be completed from grounded battery, left-hand contacts of. key

20, conductor 21, outer left-hand armature and front contact of relay 6, which is locked up as long as relay 3 1s energized, conductor 11 and the winding of relay 10 to ground. The operation of relay 10;opens the circuit through the windings of relay 4 and the left-hand winding ofrelay 7-, which relays ,then deenergize. The deenergizationeof're lay 7 disconnects the operators telephone apparatus from the cord indicated at the right, and the denergization of relay 4 completes a circuit from grounded battery, armature and back contact of relay 4, righthand contacts of listening key 20, conductor 22, right-hand "armature and front contact of relay 6, and the winding of relay 7 to ground. Relay 7 is energized as before and the connection to the operators head set is made as previously described.

It is to be noted that in this arrangement all the relays are positively actuated, no margins being employed. a

If now the operator, after inserting plug 2into jackl, thereby listening in on the cord shown at the left of the dotted line,

does not set up a number 011 her key set, the sequence switch 100 associated with such cord will not leave position 2. If she then answers another call with the cord shown at the right of the dotted line, her head set will be connected with this second cord and relay 7 will denergize. The 'deenergization of-relay 7 will complete a circuit from grounded battery, relay 25, outer left-hand armature and back contact of relay 7, contact 10a to ground. Relay 25 is energized and locks upuntil-sequence switch 100 arrives in position 1 over a circuit from grounded batteryfcontact I05, left-hand armature-and front. contact of relay 25 to ground, and completes a circuit at its righthand armature from grounded battery, power magnet of sequence switch 100, righthand armature and :front contact of relay 25 to? ground, which returns sequence switch 100 to its normal position. When sequence switch 100 arrives in its normal position, thesame conditions exist which causedfthe operators headset to be listened in on the cord shown at the left of the drawings; and if it were not for relay 6, she would be again listened in on the cord shown at the left, thereby disconnecting her from the cord shown at the right of the dotted line. This undesirable operation is prevented by the actuated condition of relay 6, which remains locked up'as long as plug 2 relnainsjin jack 1, andat its right hand arma ture holds open the circuit over which relay 7 was energized when plug 2 was first inserted in jack 1 with sequence switch 100 in position 1.

The operation" of returning sequence switch 100 to its normal position incase the operator answers another call-without depressing any keys as described, differs somewhat from that. disclosed in the above mentioned patent, since in the present invention no listening" key sequence '"switch is employed. N evertheless the operation is: fundamentally the-same, since in the system of reference the operator would: be listened outof the desired cord if she plugs in with such'cord before depressing keys associated with the cord which she had previously used to answer a call.

What is claimed is:

1. In a telephone exchange system,a plurality of subscribers lines, a plurality of link circuits for interconnecting said lines,

an operators-head set, relays, one forveach circuit, to control the connection of said head set to said link circuits, energizing cir-' cuits for said relays," locking circuits for'said relays, means for completing said energizing circuits, and automaticrneanscommon to said link circuits for opening any existing locking circuit whenever anenergizing circuit is completed.

2. In a telephone exchangesystem, a plurality of subscribers lines, a plurality of link circuits for interconnecting said lines, an operators head set,relays, one for each link circuit, to control the connection of said head set to said link circuits, energizing circuits for said relays, locking circuits for said relays, means for completing said onergizing circuits, and arelay combination common to said link circuits for opening any existing locking circuit Whenever an energizing circuit is completed.

In a telephone exchange system, a plurality cl? subscribers lines, a plurality of link cir :uits for interconnecting said lines, an operators head set, relays, one for each link circuit, to control the connection of said head set to said link circuits, energizing cir cuits for said relays, locking circuits for said relays, a pair oft relays common to said link circuits, and means including said relays for opening any existing locking circuit When ever an energizing circuit is completed.

-l. In a telephoneexchange system, a plurality of subscribers lines, a plurality of link circuits for interconnecting said lines, an operators head set, relays, one for each link circuit, to control the connection of said head set to said link circuits, energizing circuits for said relays, locking circuits for said relays, a relay common to said link circuits arranged to have its Winding included in series with said. locking circuits, a second relay common to said link circuits,said second common relay controlling at its contacts said locking circuits.

5. In a telephone exchange system, a plurality of subscribers lines, a plurality of link circuits for interconnecting said lines,

series with Whichever one of said first mentioned relays has been energized, a second relay common to said link circuits, and means including contacts of said second relay for opening said series connection.

6. in a telephone exchange system, aplurality of subscribers lines, a plurality of link circuits for interconnecting said lines, an operators head set, means to connect said head set to a link circuit, a controlling switch associated with each of said link circuits, means to advance said controlling switch to a waiting position, means to con nect said head. set to a second link circuit, means siimiltaneously operative to disconnect said head set from said first link circuit, means operative upon such disconnection to restore said controlling switch to its normal position if it is still in waiting position when such disconnection occurs, and means to prevent reconnection of said head i set to said first link circuit and disconnec- FRANKLIN A. STEAPN'.

copies 0! this patent may be obtained for five cents each. by addressing the Commissioner of Patents.

Washington, D. 0. 

